The growth of several tumors in adults is known to be modulated by sex steroids. A similar influence on tumor growth in infants and children has not been investigated extensively because it is generally assumed that the pre-pubertal hypothalamic-pituitary-gonadal (HPG) axis is dormant. The HPG axis is in fact, fully functional by 26 weeks of fetal life and remains so throughout infancy. The natural history of congenital hemangiomas, the most common tumor of infancy, reveals a striking temporal relationship between HPG axis activity and the groth and regression of these tumors. This study will investigate, in detail, the therapeutic efficacy of reversable hypothalamic-pituitary-gonadal (HPG) axis blockade with a long-acting agonist-analog of GnRH, depot leuprolide ("GnRHa"), in the treatment of congenital hemangiomas. The findings will have potential value in the treatment of these and other tumors of infancy.